With popularity of multimedia presentation and increased ease of editing, the lecturers or the presenters may directly display information in the form of a slide show in a meeting by incorporating a presentation program (e.g. PowerPoint) to edit and play slide files. For facilitating the audience well realize the presentation contents, a laser pointer is commonly used to project a point of light to highlight items of interest during a presentation.
Nowadays, with increasing awareness of environmental protection, more and more products are designed in views of power-saving concepts. For example, a power-saving device entitled “Power-saving device for visible light laser diode” is disclosed in Taiwanese Patent No. 325937, and the contents of which are hereby incorporated by reference. For achieving the power-saving purpose, based on persistence of vision and photoelectric properties of the laser diode, the visible light laser diode intermittently emits light under the circumstance imperceptible to the human beings.
FIG. 1A is a schematic timing waveform diagram illustrating a signal period T of a switching signal 101 for controlling illumination of a laser diode according to the background of Taiwanese Patent No. 325937. FIG. 1B is a schematic timing waveform diagram illustrating a signal period T of a switching signal 102 for controlling illumination of a laser diode according to a preferred embodiment of Taiwanese Patent No. 325937.
As shown in FIG. 1A, each signal period T of a switching signal 101 includes an on duration Ton and an off duration Toff, wherein the on duration Ton is equal to an off duration Toff. The switching signal 101 is maintained at a high level during the on duration Ton but maintained at a low level during the off duration Toff. In response to the switching signal 101 at the high level, the laser diode (not shown) emits light beams. Whereas, in response to the switching signal 101 at the low level, the illumination is interrupted.
The switching signal 102 of FIG. 1B is used for improving intermittent illumination according to a preferred embodiment of Taiwanese Patent No. 325937. The switching signal 102 of FIG. 1B is distinguished from the switching signal 101 of FIG. 1A in that there are several alternate high and low levels during the on duration Ton. Similarly, the laser diode of FIG. 1B emits light beams in response to the switching signal 102 at the high level in order to reduce the lighting time intervals and achieve the power-saving purpose.
Although the power-saving device utilizing the switching signal of FIG. 1B can achieve the power-saving purpose, there are still some drawbacks. For example, if the time intervals of the high levels of the switching signal 102 are too short, the laser light beams twinkle and appear dim and obscure. On the other hand, for achieving optimal brightness of laser light beams, the use of the switching signal 101 is more feasible but the power consumption is increased.
Therefore, there is a need of providing a power-saving laser pointer mouse with enhanced power-saving efficiency and desired brightness of laser light beams.